Molecular Detection of Phytophthora colocasiae of Taro Leaf Blight Based on PCR

The present PCR assay was conducted to develop rapid and sensitive detection of Phytophthora colocasiae,in order to provide a robust and reliable tool for healthy seedling production of taro and limiting the transmission and spread of the causal organism of taro leaf blight in taro planting regions.The samples were used to extract total DNA and to be detected by PCR with P.colocasiae specific primer pairs PCSP-RL F/PCSP-RL R and PCSP-T F/PCSP-T R,respectively.Distinct fragments of about 200 bp and 240 bp were amplified by PCR using primers PCSP-RL F/PCSP-RL R and PCSP-T F/PCSP-T R,respectively.The analysis of the nucleotide sequence of the PCR products were found to be 99% identical to sequence of RAS-related protein (Ypt1) and phospho-ribosylanthranilate isomerase (TRP1) in P.colocasiae,respectively.It is concluded that rapid and sensitive developed PCR assay for detection of P.colocasiae could be used in routine diagnosis and aid in management practices to mitigate taro leaf blight.

芋种质资源开花结实状况调查

对保存在国家种质武汉水生蔬菜资源圃中的芋属种质资源的开花结实状况调查表明:在自然条件下,所有滇南芋(2n=2x)中的野芋和花用芋资源全部开花;芋开花状况表现为:魁芋(2n=2x)、多头芋(2n=3x)、魁子兼用芋(2n=3x)都不开花;国内多子芋中,紫柄多子芋(2n=3x)都不开花,乌绿柄多子芋(2n=3x)和绿柄多子芋(2n=3x)有部分品种开花,但开花的品种具有不确定性;来源于东南亚国家的多子芋中,绿柄多子芋(2n=2x)开花率高,花期长,另有1份紫柄多子芋(2n=3x)开花,与国内多子芋(2n=3x)差异较大。开花率表现为东南亚多子芋等于或高于国内芋;国内芋中,二倍体的大于三倍体的。花期最长的是东南亚绿柄多子芋(2n=2x),国内芋中,二倍体的花期长于三倍体的。乌绿柄多子芋和花用芋的芽色都为红色,属于短附属器,其余类型的芽色为白色,属于长附属器。在自然条件下,仅有2份紫柄野芋种质结实,其他种质未见结实。本研究还对不同类型芋的始花期、末花期、花期、单株花序丛数、单个叶轴花序数、单株总花序数和佛焰苞管部、佛焰苞檐部、附属器、雄花序、中性花序、雌花序的长度等进行了比较。

我国芋头栽培技术研究进展

芋头(Colocasia esculenta)的营养价值和经济价值高。我国的芋头资源极为丰富,但开发程度远不及山药、甘薯、马铃薯等块茎和块根作物,因而芋头研究的深入对其开发利用具有重要意义。综述了我国芋头栽培技术的研究进展。

芋氮磷钾吸收规律的研究

采用凯氏定氮法、钼锑抗显色法、火焰光度计法对芋[Colocasia esculenta(L.)schott]的两个品种各器官中的氮、磷、钾含量进行测定,研究芋植株对氮磷钾的吸收与分配规律。结果表明,在幼苗期,氮磷钾的分配主要集中在芋的叶片和叶柄中,氮以叶片中居多,钾以叶柄中居多;从发棵期开始,氮磷钾主要分配在芋的球茎中。

芋“3414”肥效试验与配方施肥推荐研究初报

开展"3414"肥效试验,研究了不同肥料配比对芋(Colocasia esculenta)及芋荷梗产量的影响,建立了氮、钾肥施肥量与产量的回归方程,探索了获得芋及芋荷梗的最佳施肥量。结果表明,合理施肥可有效提高芋及芋荷梗的产量,且对芋荷梗的增产效果更加明显,过量施用钾肥会造成芋及芋荷梗产量明显降低,若以芋荷梗为主要采收目标时,可适当增加氮、钾肥的施用量。在该试验土壤条件下,推荐施肥量为氮肥225.0~337.5 kg/hm^2,钾肥171.0~235.5 kg/hm^2。

芋头叶柄泡菜泡制工艺优化及其香气物质研究

以芋头[Colocasia esculenta(L.)Schott]叶柄为原料,用防腐剂调节芋头泡菜中的菌落总数和pH,用酸度指标来筛选、复配防腐剂,选出最佳防腐剂浓度;以感官评分为标准,优化芋头叶柄泡菜的泡制工艺;采用顶空-固相微萃取与气相色谱质谱联用法(SPME-GC-MS)分析芋头叶柄泡菜中的香气物质成分,研究增味剂对芋头叶柄泡菜香气物质成分的影响。结果表明,常温条件下最佳防腐剂浓度为山梨酸钾0.63 g/kg、脱氢乙酸钠0.36 g/kg;低温条件下最佳防腐剂浓度为山梨酸钾0.30 g/kg、脱氢乙酸钠0.50 g/kg、焦亚硫酸钠0.02 g/kg;最佳增香效果条件为增味剂0.03 g/kg,山梨酸钾0.60 g/kg,泡菜不做前处理。一定量的增味剂对芋头叶柄泡菜有提鲜、增进风味的作用,0.03 g/kg增味剂浓度中含有较多的酯类、醇类物质,且酸类物质适中,口感相对较好。

Transcriptome analysis of purple pigment formation in Colocasia esculenta

Taro(Colocasia esculenta(L.)Schott)is an important crop in Africa,Southeast Asia,and subtropics and is used as a food and medicine.The purple color pigmentation is an appealing character in taro.We sampled taro corms of the cultivar‘Lipu Taro’at four developmental stages,including LPYS1(without purple pigment,50 days of development(DOD)),LPYS2(very few purple pigments,75 DOD),LPYS3(moderate purple pigments,115 DOD)and LPYS4(high purple pigments,205 DOD).The purpose of our study was to identify the key genes underpinning the purple pigmentation in taro based on RNA-sequencing.Through RNA-Seq,6453 differentially expressed transcripts(DETs)were identified between purple and non-purple pigmented samples.We identified 41 and 12 flavonoid and anthocyanin related DETs transcripts,respectively.These DETs were upregulated at LPYS2,LPYS3,and LPYS4 as compared to LPYS1,indicating their positive contribution to the color formation in taro.Moreover,we identified several DETs encoding for transcription factors,including MYB and bHLH,known to be major regulators of structural genes involved in the flavonoid-anthocyanin pathway.Finally,we reported several plant hormones(ethylene,auxin,gibberellin,jasmonic acid,and cytokinin)related DETs,which are predicted to play important roles in the corm coloration.Different regulation of transcripts representing the flavonoid-anthocyanin biosynthesis pathway,plant hormone transduction pathway,and transcription factors may have key roles in purple pigmentation in taro.Our findings will facilitate future research on improving the quality and appeal of taro.

Synthesis of silver nanoparticle with Colocasia esculenta(L.) stem and its larvicidal activity against Culex quinquefasciatus and Chironomus sp

Objective:To synthesize silver nanoparticles with Colocasia esculenta as a reducing agent and to evaluate their effect against Culex quinquefasciatus and Chironomus sp.Methods:The aqueous extract of Colocasia esculenta stem was used for nanosynthesis.The synthesized nanoparticles were characterized by UV-Vis spectrophotometry,Fourier-transform infrared spectroscopy,scanning electron microscope,transmission electron microscopy,energy-dispersive X-ray spectroscopy,X-ray diffraction and Zeta potential studies.The toxicity of Colocasia esculenta stem extract and the synthesized silver nanoparticles was evaluated against the larval stages of target human filarial vector Culex quinquefasciatus and non-target Chironomus sp.Results:Scanning electron microscopy and transmission electron microscopy studies revealed almost spherical shape of the synthesized silver nanoparticles with size ranging from 13-50 nm.After 24 hours of exposure,the LC50 and LC90 of the plant extract against 4th instars larvae of Culex quinquefasciatus were 745.56 mg/L and 1258.28 mg/L,respectively,which were higher than those of synthesized silver nanoparticles(5.17 mg/L and 17.32 mg/L after 24 h;1.58 mg/L and 13.01 mg/L after 48 h).In addition,the LC50 and LC90 of silver nanoparticles against Chironomus sp.were 9.71 mg/L and 23.15 mg/L after 24 h as well as 2.38 mg/L and 19.49 mg/L after 48 h,respectively.Conclusions:The aqueous stem extract of Colocasia esculenta is a good agent for synthesis of silver nanoparticles,which are almost spherical with size less than 30 nm.The synthesized nanoparticles show good larvicidal activity without any harmful effect on non-target species.

Improvement of Two-Dimensional Gel Electrophoresis for Study of Corm Formation Related Proteins in vitro from Taro (Colocasia esculenta)

Efficient and reproducible sample preparation prior to 2D-PAGE (two-dimensional polyacrylamide gel electrophoresis) is a critical step in achieving accurate and reliable data. In this paper, we described a method to prepare protein samples of taro that was compatible with subsequent analysis using 2D-PAGE. We compared proteins from shoot basal region from 0 d and 2 d after the beginning of tuberization. By this method we got about (2 000) spots and high reproducibility. Additionally some changes of protein expression were found.

<i>In Vitro</i>Organogenesis of <i>Colocasia esculenta</i>cv. <i>Antiquorum</i>L.

In vitro organogenesis of an upland species of Colocasia esculenta cv. antiquorum L. was examined in relation to different explants like meristem and parenchymatous storage tissues with or without anthocyanin layer, four levels of each of Kn, 2,4-D, NAA and BAP and four incubation environments such as: 1) 16 h 3 Kl light intensity + 24°C ± 2°C;2) 24 h dark + 24°C ± 2°C;3) 24 h dark + 30°C ± 3°C and 4) 12 h diffuse light + 30°C ± 3°C. Only meristems showed proliferation with various degree of intensity both at 16 h 3 Kl light + 24°C ± 2°C and 24 h dark + 24°C ± 2°C conditions and poor response with different levels of Kn + NAA either in light or in the dark. Cultures with NAA + BAP were proliferated very quickly with very high degree of intensity. The cultures under dark did not proliferate for 20 days which upon transfer to light showed high degree of proliferation. Cultures with NAA + BAP formed calluses more pronouncedly at dark than that occurred in the light. Parenchymatous tissues with or without anthocyanin did not proliferate but the tissues with anthocyanin lost pigmentation after 25 - 30 days and turned to grey colour after 50 days while tissues without anthocyanin turned to green colour with shinny pimples indicating that protocorm may be developed. No culture under high temperature environment (30°C ± 3°C) neither survived nor proliferated. The meristems in culture were died within 15 - 20 days while others within 25-30 days. In conclusion, a combination of NAA (0.5 - 3.0 mg/l) and BAP (0.5 - 2.0 mg/l) and an incubation photoperiod of 16 h coupled with temperature of 24°C ± 2°C were found most suitable for in vitro culture of Colocasia esculenta cv. antiquorum L.

Morphological Comparison of Five Varieties of <i>Colocasia esculenta</i>(L.) Schott in Anambra State, Southeastern Nigeria

Comparative morphological study of five varieties of Colocasia esculenta (L.) Schott present in Anambra State, Nigeria was carried out, in order to furnish plant taxonomists with information which could be of great help in delimitation of the varieties. Significant difference was established at p < 0.05. The result showed that adaxial surface of “kochuo” had a purplish dot on the centre, abaxial leaf surface had a conspicuous purplish colour at the point of attachment to the leaf, and the cormels had numerous striking vertical purple stripes on the surface. There was presence of foliaceous (leaf-like) appendages at the veins of the abaxial surface of the leaf of “ogeriobosi”. The leaf length ranged from 35.6 ± 7.70 cm (“kochuo”) to 49.9 ± 3.55 cm (“ogeriobosi”). Petiole length of “ogeriobosi” was the highest (63.3 ± 3.83 cm), whereas the least was Colocasia esculenta var. antiquorum (26.67 ± 2.20 cm). The corm length ranged from 4.10 ± 0.10 cm (Colocasia esculenta var. antiquorum) to 8.60 ± 0.35 cm (“ogeriobosi”), while the cormel length ranged from 3.70 ± 0.96 cm (Colocasia esculenta var. antiquorum) to 7.03 ± 0.36 cm (“ogeriobosi”). This work has revealed diagnostic and differential morphological characters, which could be useful for identification and description of varieties of C. esculenta. In addition, it provided additional information which might be helpful in resolving the on-going controversy in the taxonomy of Colocasia, which would, in turn, probably lead to possible delimitation of C. esculenta.

Characterization of a Highly Potent Insecticidal Lectin from <i>Colocasia esculenta</i>Tuber and Cloning of Its Coding Sequence

Hemipteran insects are the most devastating pest for different crops of high economic value. Colocasia esculenta tuber agglutinin (CEA), a mannose binding monocot lectin from araceae family was previously reported by the present group to be effective against some members of this class of pests. In the present study, efficacy of this potent lectin has been extended to cotton aphid (Aphis gossypii) which is becoming a highly damaging pest of cotton in recent days. Because, like other aphids, A. gossypii not only extracts the phloem fluid but also transmit disease causing viruses and add to the high degree of yield loss. Efficacy of the lectin on cotton aphid as well as other hemipteran insects prompted us further to clone the protein coding gene. Very little sequence information of this gene was available in the database. Hence, attempt had been made to study the protein through liquid chromatography-tandem mass spectrometry (LC-MS/MS) to have the detailed peptide information. On the basis of the peptide homology information obtained from LC-MS/MS the complete coding sequence of CEA was determined. The coding sequence corresponding to CEA was cloned further using primers designed on the basis of above information and genome walk technology for its potential utilisation in insect management programme.

Effect of Different Levels of Nitrogen on Yield of Colocasia (<i>Colocasia esculenta</i>) at District Malakand Dargai

A field experiment was conducted to evaluate the response of colocasia (Colocasia esculenta) to different levels of 0, 60, 90, 120 and 150 kg N ha-1 under farmer’s field condition at Garhi Usmani Khel, District Malakand Dargai during 2013. The experiment was laid out in Randomized Complete Block design with three replications and treatment plot size of 2.74 × 2.43 m2. All levels of N in the form of urea along with uniform basal doze of 90 kg P2O5 ha-1 as Triple Super Phosphate (TSPPP) were applied to soil at time of seed bed followed by thorough mixing. Seeds of colocasia c.v. local variety were sown in these plots with row spacing of 30 cm and plant to plant distance of 12 cm in February, 2013. The results showed that application of N produced significantly higher colocasia tuber yield, number of tubers plant-1, 1000-tubers weight and size of tubers (mean length and diameter) over control but the differences among levels of N were nonsignificant. However, some parameters like tuber yield was maximum at 60 kg N ha-1 and tuber size especially the length of colocasia tuber was maximum at 150 kg N ha-1 suggesting that the response of each parameter was different to N levels. Based on maximum relative yield (100%) and increase over control (46.1%) still at lower N levels of 60 kg N ha-1, this level seems to be appropriate level for colocasia under the prevailing soil and climatic conditions.

Cocoyam (corms and cormels)—An underexploited food and feed resource

Cocoyams (old-taro: Colocasia esculenta;newtannia: Xanthosoma sagittifolium) yield corms as root crops produced in regions of tropical and subtropical developing countries. In certain countries such as Ghana, there are surpluses in production but deficits in cereals. Cocoyams are used in a range of indigenous foods. Post harvest losses are high due to mechanical damage of corms during harvest and microbial attacks on such damaged corms during storage. Cocoyams contain, on average, 25% starch (wet weight basis) with A-type structures characterized by small granule size (<1.5 μm). Non-starch polysaccharides in cocoyams confer gummy properties to the starch. However, mechanical effects of raphides—crystals of calcium oxalate and other components—produce irritation when raw corm tissue is ingested resulting in several levels of discomfort. With appropriate processing, cocoyams could be a rich source of starch for food and industrial applications and corms have potential for new product development. Stabilizing cocoyam crops and adding value could greatly improve its utilization in cocoyam producing countries.

Evaluation of the Value Nutritious Leaves Five Varieties Taro (Colocasia esculenta) Cultivated in Burkina Faso

Taro is a perennial herbaceous plant whose large leaves are mainly used as vegetables in human food in several tropical countries. However, young taro leaves are not eaten very much in Burkina Faso unlike other countries which have made them a staple diet. In the present work, we collected leaves of taro varieties cultivated in the provinces of Comoe and Kenedougou. Our study aimed to determine the biochemical composition of these leaves in order to detect their nutritional quality. For this purpose, we first determined the total sugars in our different samples;then quantify the proteins and finally assay the lipids contained in the leaves of the different varieties of taro harvested. Analysis of the organic constituents gave the following results: proteins (186.29 to 265.23 μg EQ/100mg fresh leaves), fats (0.28% to 1.90%), carbohydrates (183.03 to 238.57 μg EG/100mg fresh leaves). The highest energy value was obtained with the variety BF/CO/06 (1728.71 kcal/kg) and the lowest with BF/CO/04 (272.15 kcal/kg). This study allowed us to conclude that the taro leaves (Colocasia esculenta) studied are of nutritional interest with regard to their biochemical composition.

Genetic Diversity of Taro Landraces from Côte d’Ivoire Based on Qualitative Traits of Leaves

Taro is an important crop species in Côte d’Ivoire. It is cultivated for its tubers and leaves. But its knowledge and genetic diversity and differentiation are very weakly documented. Several morphological types are found in rural area, but their identification is not very clear, and their agronomic potentiality is underexploited. In this context we initiated a survey and collected 213 accessions from 14 growing regions of Côte d’Ivoire. The diversity was evaluated based on seven qualitative traits of leaves (Shape of the base of the leaf, Predominant position (shape) of the leaf blade surface, Margin of the leaf blade, Leaf blade variegation, Profile of the petiolar junction, Shape of the leaf sheath, Shape of the appendix) during an experimentation conducted in rural area. The objective of this study was to characterize the collection of taros collected in different geographical zones of Côte d’Ivoire and identify the genera cultivated. Results of our study indicated that excepted margin of the leaf blade all traits are very discriminant. Several variants were observed for each of traits. According to observations and statistics analysis accessions were separated into two main groups. The characteristics of these groups indicate that taro cultivated in Côte d’Ivoire could belong to two genera: Xanthosoma and Colocasia.

Comparison of the Effectiveness of Different Traditional Soaking Processes on the in Vitro Digestibility of Taro(Colocasia esculenta L.SCHOTT)Flour

A traditional process used by farmers in Chad consists in soaking slices of taro (Colocasia esculenta L. SCHOTT) in tamarind infusion, or in corn solution or in water over a 24-hour period to reduce the acridity of taro and facilitate cooking. The aim of this study was to assess the effect of traditional soaking on the in vitro digestibility of taro flour using or not using an α-amylase enzyme. The digestion without the enzyme has shown that the soaking processes improve the digestibility of taro flour (from 39.30% for the control sample to 75.11% (after tamarind infusion) and 78.67% (treatment with water) after 24 hours of soaking). Soaking over a 6-hour period and preferentially in tamarind infusion or in corn solution obtains highly digestible flour (around 95% of digestibility rate after 3 hours of enzymatic digestion).

^14CO2 Fixation and Translocation of Photoassimilates as Selection Criteria of Egyptian Taro Genotypes

The growth characterlstlcs, different physlological parameters, photosynthetic activity （^14CO2 fixation）, and the translocatlon rate of photoassimllates In different taro （Colocasia esculenta L. Schott） genotypes was studled In order to determlne the posslble use of these parameters as selectlon crlterla for dlfferent wldely used genotypes of taro （Delta No. 9, 15, 20, 21, and balady）. The results obtalned suggest that Delta No. 21 shows the most slgnlflcant increase In all parameters tested compared wlth the control （balady）, followed by Delta No. 9, 15, and 20, respectively. The results show a positive correlation between photosynthetlc actlvlty, translocatlon efflclency, and total yield. The selected clone Delta No. 21 Is recommended for cultlvatlon In the delta reglon of Egypt.